A pressure vessel is used as a fuel tank for storing a fuel gas for an automobile or the like (for example, compressed natural gas: CNG) at high pressure. In recent years, from a viewpoint of environmental protection and needs of users, there has been an increasing demand for reducing fuel consumption of automobiles or the like. Accordingly, a smaller and lighter fuel tank equipped in an automobile or the like has been strongly desired. A toroidal pressure vessel has higher pressure resistance and is capable of storing gas at higher pressure compared with a cylindrical pressure vessel, for example, and hence it is possible to reduce the size of the pressure vessel while maintaining the gas storage capacity.
For example, in the pressure vessel of Patent Literature 1, the pressure resistance is enhanced by arranging meridional reinforcing fibers and latitudinal reinforcing fibers on the surface of the toroidal inner vessel. Specifically, the meridional reinforcing fibers are used for restricting expansion of the pressure vessel in the meridional cross-section of the toroidal, and the latitudinal reinforcing fibers are used for restricting expansion of the pressure vessel in the latitudinal cross-section of the toroidal, thereby improving the pressure resistance. Note that, the meridional direction is a direction of a plane which includes an axis (indicated by C of FIG. 1) of the toroidal shape (direction indicated by M of FIG. 1), and the latitudinal direction is a direction of a plane orthogonal to the central axis (direction indicated by L of FIG. 1).